The present invention relates to manufacturing group IV element alloys.
Semiconductor materials based on silicon technology are utilized extensively in electronics. The inherent electronic properties of silicon, however, limit silicon applications in optoelectronic devices and very high speed electronic devices.
Alloys of group IV elements, which include carbon (C), silicon (Si), germanium (Ge), tin (Sn), and lead (Pb), have been investigated for their utility in semiconductor devices. Group IV elements are isoelectronic and, as a result, have similarities in their physical and chemical properties. Except for lead, all of the first four group IV elements have stable or metastable phases in diamond-cubic crystal structure, which is the crystal structure of semiconductor silicon. Bulk Sn transforms from .alpha.-phase (i.e., diamond-cubic) to .beta.-phase (i.e., body centered tetragonal) at about 13.2.degree. C. Thin film .alpha.-Sn, however, can be epitaxially stabilized on substrates with similar lattice constants at much higher temperatures (e.g., about 130.degree. C.).
SnGe is a thermodynamic metastable group IV alloy that exhibits a simple eutectic system having a eutectic temperature of about 231.degree. C., with mutual equilibrium solubilities no more than 1 atomic %. The limited solid solubility and the surface free energy difference between Sn and Ge, tend to cause Sn to segregate to the surface during SnGe alloy growth.